Waveform generating device, waveform generating method, and charged particle beam irradiation apparatus

Abstract

In one embodiment, a waveform generating device includes a first DA converter converting input data, a controller outputting a first signal having a command value based on the input data, and a second signal having a command value differing by a constant value from the first signal, a second DA converter converting the first signal, a third DA converter converting the second signal, and a combiner combining the output of the first DA converter, the output of the second DA converter, and the output of the third DA converter. When a value of a predetermined first high-order bit of the input data is inverted, the controller changes the command value of the first signal such that a value of the first high-order bit or a second high-order bit different from the first high-order bit is inverted.

What is claimed is: 
     
       1. A waveform generating device comprising:
 a first DA converter converting input data from digital to analog and provide an output; 
 a controller outputting a first signal having a command value based on the input data, and a second signal having a command value differing by a constant value from the command value of the first signal; 
 a second DA converter converting the first signal from digital to analog and provide an output; 
 a third DA converter converting the second signal from digital to analog and provide an output; and 
 a combiner combining the output of the first DA converter, the output of the second DA converter, and the output of the third DA converter, 
 wherein when a value of a predetermined first high-order bit of the input data is inverted, the controller changes the command value of the first signal such that a value of the first high-order bit or a second high-order bit different from the first high-order bit is inverted. 
 
     
     
       2. The form generating device according to  claim 1 , wherein the combiner includes a first subtractor subtracting the output of the third DA converter from the output of the second DA converter, and a second subtractor subtracting an output of the first subtractor from the output of the first DA converter. 
     
     
       3. The waveform generating device according to  claim 1 , wherein the command value of the first signal and the command value of the second signal differ by one least significant bit. 
     
     
       4. The waveform generating device according to  claim 1 , wherein the waveform generating device includes a plurality of second DA converters; and
 the command value of the first signal received by each of the second DA converters is different in terms of an inverted bit, or is the same in terms of an inverted bit but different in the value of a higher-order bit than the inverted bit. 
 
     
     
       5. The waveform generating device according to  claim 4 , wherein the plurality of second DA converters amplify signals by different amplification factors and output the amplified signals. 
     
     
       6. A waveform generating method comprising:
 converting input data from digital to analog using a first DA converter and outputting a voltage; 
 outputting to a second DA converter a first signal having a command value based on the input data, converting the first signal from digital to analog, and providing an output; and 
 outputting to a third DA converter a second signal having a command value differing by a constant value from the command value of the first signal, converting the second signal from digital to analog, and providing an output, 
 wherein when a value of a predetermined first high-order bit of the input data is inverted, the command value of the first signal is changed such that a value of the first high-order bit or a second high-order bit different from the first high-order bit is inverted; and 
 the output of the first DA converter, the output of the second DA converter, and the output of the third DA converter are combined to obtain a signal having a glitch that is smaller in magnitude than a glitch included in the output of the first DA converter. 
 
     
     
       7. The waveform generating method according to  claim 6 , wherein the output of the third DA converter is subtracted from the output of the second DA converter using a first subtractor; and
 an output of the first subtractor is subtracted from the output of the first DA converter using a second subtractor to obtain a signal having the glitch reduced in magnitude. 
 
     
     
       8. The waveform generating method according to  claim 6 , wherein the command value of the first signal and the command value of the second signal differ by one least significant bit. 
     
     
       9. The waveform generating method according to  claim 6 , wherein the first signal is output to each of a plurality of second DA converters, converted from digital to analog, and output; and
 the command value of the first signal received by each of the second DA converters is different in terms of an inverted bit, or is the same in terms of an inverted bit but different in the value of a higher-order bit than the inverted bit. 
 
     
     
       10. The waveform generating method according to  claim 9 , wherein the plurality of second DA converters are configured to amplify signals by different amplification factors and output the amplified signals. 
     
     
       11. A charged particle beam irradiation apparatus comprising:
 an emitting unit emitting a charged particle beam, 
 a stage holding a substrate thereon; 
 a deflection control circuit including the waveform generating device according to  claim 1 , the deflection control circuit outputting deflection data for deflecting the charged particle beam; 
 a deflector deflecting the charged particle beam in accordance with the deflection data from the deflection control circuit; and 
 a writer writing a pattern onto the substrate using the charged particle beam while moving a deflection position of the charged particle beam on the substrate. 
 
     
     
       12. The charged particle beam irradiation apparatus according to  claim 11 , wherein the combiner includes a first subtractor subtracting the output of the third DA converter from the output of the second DA converter, and a second subtractor subtracting an output of the first subtractor from the output of the first DA converter. 
     
     
       13. The charged particle beam irradiation apparatus according to  claim 11 , wherein the command value of the first signal and the command value of the second signal differ by one least significant bit. 
     
     
       14. The charged particle beam irradiation apparatus according to  claim 11 , wherein the waveform generating device includes a plurality of second DA converters; and
 the command value of the first signal received by each of the second DA converters is different in terms of an inverted bit, or is the same in terms of an inverted bit but different in the value of a higher-order bit than the inverted bit. 
 
     
     
       15. The charged particle beam irradiation apparatus according to  claim 14 , wherein the plurality of second DA converters amplify signals by different amplification factors and output the amplified signals. 
     
     
       16. A charged particle beam irradiation apparatus comprising:
 an emitting unit emitting a charged particle beam; 
 a stage holding a substrate thereon; 
 a writer including a deflector configured to deflect the charged particle beam, the writer writing a pattern onto the substrate using the charged particle beam while moving the stage and moving a deflection position of the charged particle beam on the substrate in such a manner as to follow the movement of the stage; and 
 a deflection control circuit outputting deflection data for deflecting the charged particle beam to the deflector, 
 wherein the writer causes a tracking amplifier to move the deflection position of the charged particle beam on the substrate in such a manner as to follow the movement of the stage, the tracking amplifier including the waveform generating device according to  claim 1 . 
 
     
     
       17. The charged particle beam irradiation apparatus according to  claim 16 , wherein the combiner includes a first subtractor subtracting the output of the third DA converter from the output of the second DA converter, and a second subtractor subtracting an output of the first subtractor from the output of the first DA converter. 
     
     
       18. The charged particle beam irradiation apparatus according to  claim 16 , wherein the command value of the first signal and the command value of the second signal differ by one least significant bit. 
     
     
       19. The charged particle beam irradiation apparatus according to  claim 16 , wherein the waveform generating device includes a plurality of second DA converters; and
 the command value of the first signal received by each of the second DA converters is different in terms of an inverted bit, or is the same in terms of an inverted bit but different in the value of a higher-order bit than the inverted bit. 
 
     
     
       20. The charged particle beam irradiation apparatus according to  claim 19 , wherein the plurality of second DA converters amplify signals by different amplification factors and output the amplified signals.